The Influence of Fruit Load on the Tomato Pericarp Metabolome in aSolanum chmielewskiiIntrogression Line Population

Abstract

It has been recently demonstrated, utilizing interspecific introgression lines of tomato, generated from the cross between Solanum lycopersicum and the wild species Solanum pennellii, that the efficiency of photosynthate partitioning exerts a considerable influence on the metabolic composition of tomato fruit pericarp. In order to further evaluate the influence of source-sink interaction, metabolite composition was determined by gas chromatography-mass spectrometry in a different population. For this purpose, we used 23 introgression lines resulting from an interspecific cross between S. lycopersicum and the wild species Solanum chmielewskii under high (unpruned trusses) and low (trusses pruned to one fruit) fruit load conditions. Following this strategy, we were able to contrast the metabolite composition of fruits from plants cultivated at both fruit loads as well as to compare the network behavior of primary metabolism in the introgression line population. The study revealed that while a greater number of metabolic quantitative trait loci were observed under high fruit load (240) than under low fruit load (128) cultivations, the levels of metabolites were more highly correlated under low fruit load cultivation. Finally, an analysis of genotype × fruit load interactions indicated a greater influence of development and cultivation than genotype on fruit composition. Comparison with previously documented transcript profiles from a subset of these lines revealed that changes in metabolite levels did not correlate with changes in the levels of genes associated with their metabolism. These findings are discussed in the context of our current understanding of the genetic and environmental influence on metabolic source-sink interactions in tomato, with particular emphasis given to fruit amino acid content.

Identification and Mode of Inheritance of Quantitative Trait Loci for Secondary Metabolite Abundance in Tomato

“…While only a handful of studies have used broad genetic crosses to identify mQTLs for a broad range of secondary metabolites (Kliebenstein et al, 2001a(Kliebenstein et al, , 2001bKeurentjes et al, 2006;Morreel et al, 2006;Khan et al, 2012;Matsuda et al, 2012;Routaboul et al, 2012;Gong et al, 2013;Wahyuni et al, 2014) and previous studies have largely been focused on Arabidopsis, considerable research has been focused on defining QTLs for volatile organic compounds from tomato fruit (Tieman et al, 2006;Mathieu et al, 2009;Mageroy et al, 2012;Rambla et al, 2014) and acyl-sugars in tomato leaf trichomes (Schilmiller et al, 2012(Schilmiller et al, , 2010. In addition, the levels of primary metabolites have been evaluated in multiple different breeding populations (Schauer et al, , 2008Do et al, 2010) as well as in association mapping panels (Sauvage et al, 2014). These previous studies provide an interesting context in which to evaluate the results of this study.…”

“…They have revealed the critical importance of cell wall invertase and fruit yield (Fridman et al, 2004;Ruan et al, 2012) and have identified the genomic regions underlying vitamin content in fruit (Stevens et al, 2007;Fitzpatrick et al, 2013;Quadrana et al, 2013Quadrana et al, , 2014. In addition, these studies highlighted a strong negative correlation between fruit amino acid content and the harvest index (i.e., the ratio of total fruit weight to total plant weight; Schauer et al, 2006;Do et al, 2010). Targeted QTL analyses have also been performed on volatile organic compounds, pigments, cell wall components, sesquiterpenes, and acyl-sugars in the Solanum pennellii introgression line population (Liu et al, 2003;Tieman et al, 2006;Fraser et al, 2007;Schilmiller et al, 2010;de Godoy et al, 2013).…”

“…In tomato, the majority of both natural variance and metabolite quantitative trait loci (mQTL) studies have focused on primary metabolism (Schauer et al, 2005(Schauer et al, , 2008Stevens et al, 2007;Do et al, 2010;Maloney et al, 2010;Quadrana et al, 2013Quadrana et al, , 2014. They have revealed the critical importance of cell wall invertase and fruit yield (Fridman et al, 2004;Ruan et al, 2012) and have identified the genomic regions underlying vitamin content in fruit (Stevens et al, 2007;Fitzpatrick et al, 2013;Quadrana et al, 2013Quadrana et al, , 2014.…”

Genetic Diversity in Tomato (Solanum lycopersicum) and Its Wild Relatives

“…Further than identify and quantify compounds, metabolomics can be of great help to decipher biosynthetic pathways (Keurentjes 2009). Metabolome studies can be combined to transcriptomic data to identify the key factors (Mounet, Moing et al 2009;Do, Prudent et al 2010). Metabolomics has an important role to play in characterization of natural diversity in tomato (Schauer, Zamir et al 2004;Fernie et al 2011).…”

“…Metabolite QTL (mQTL) can be now identified for non-volatile metabolites like sugars, pigments or volatiles compounds (Bovy, Schijlen et al 2007). This was done on several interspecific populations, notably on S. lycopersicum x S. Chmielewskii (Do, Prudent et al 2010) and intraspecific crosses (Saliba-Colombani et al 2001;Causse, SalibaColombani et al 2002;Zanor, Rambla et al 2009). Recent technologies allowed screening for diversity in a wide range of components on whole genomes.…”